After Priority: Palaven, talk to Liara in the Presidium Commons on the Citadel. She will send you to talk to Barla Von, who is in the bank in the Commons. Talking to Barla Von will actually get you the quest.

After talking to Barla Von in the Presidium Commons, proceed to the Krogan DMZ and travel to the Dranek System. Note: This only becomes visible on the galaxy map after completing Priority Sur'Kesh. The Shadow Broker Wet Squad can be obtained by scanning the planet Rothla. After you have done this, travel back to the Citadel and speak with Barla Von to complete the mission.